asp: Avoid double-free of received msg if conn is teared down

"""
20250516192255921 DLSS7 DEBUG IPA_ASP(ipa-asp-loadshare-sender0){WAIT_ID_RESP}: Received Event IPA_CCM_ID_RESP (ipa.c:120)
20250516192255921 DLMI DEBUG Rx IPA CCM ID_RESP: Unit_ID='0/1/2' MAC_Address='' Location_1='' Location_2='' Equipment_Version='' Software_Version='' Unit_Name='mahlzeit' Serial_Number=''  (ipa.c:233)
20250516192255921 DLSS7 NOTICE IPA_ASP(ipa-asp-loadshare-sender0){WAIT_ID_RESP}: Cannot find any definition for IPA Unit Name 'mahlzeit' (xua_asp_fsm.c:968)
20250516192255921 DLSS7 INFO ipa-asp-loadshare-sender0: connection closed (ss7_asp.c:1159)
20250516192255921 DLSS7 DEBUG IPA_ASP(ipa-asp-loadshare-sender0){WAIT_ID_RESP}: Received Event SCTP-COMM_DOWN.ind (ss7_asp.c:1165)
20250516192255922 DLSS7 DEBUG IPA_ASP(ipa-asp-loadshare-sender0){WAIT_ID_RESP}: state_chg to ASP_DOWN (xua_asp_fsm.c:1154)
20250516192255922 DLSS7 DEBUG XUA_AS(ipa-as-loadshare-sender){AS_DOWN}: Received Event ASPAS-ASP_DOWN.ind (xua_asp_fsm.c:370)
20250516192255922 DLSS7 DEBUG IPA_ASP(ipa-asp-loadshare-sender0){ASP_DOWN}: No Layer Manager, dropping M-ASP_DOWN.indication (xua_asp_fsm.c:119)
20250516192255922 DLSS7 DEBUG IPA_ASP(ipa-asp-loadshare-sender0){ASP_DOWN}: No Layer Manager, dropping M-SCTP_RELEASE.indication (xua_asp_fsm.c:119)

Program terminated with signal SIGABRT, Aborted.
 #0  0x000076bb9898ceec in ?? () from /lib/x86_64-linux-gnu/libc.so.6
 #0  0x000076bb9898ceec in ?? () from /lib/x86_64-linux-gnu/libc.so.6
 #1  0x000076bb9893dfb2 in raise () from /lib/x86_64-linux-gnu/libc.so.6
 #2  0x000076bb98928472 in abort () from /lib/x86_64-linux-gnu/libc.so.6
 #3  0x000076bb98ae6496 in ?? () from /lib/x86_64-linux-gnu/libtalloc.so.2
 #4  0x000076bb98b1b869 in msgb_free (m=0x5f957de3e750) at ../../../src_copy/libosmocore/src/core/msgb.c:119
 #5  0x000076bb98bab8c8 in ipa_rx_msg_ccm (asp=0x5f957de3da50, msg=0x5f957de3e750) at ../../src_copy/libosmo-sigtran/src/ipa.c:137
 #6  0x000076bb98bac135 in ipa_rx_msg (asp=0x5f957de3da50, msg=0x5f957de3e750, sls=0 '\000') at ../../src_copy/libosmo-sigtran/src/ipa.c:321
 #7  0x000076bb98bca44f in ss7_asp_ipa_srv_conn_rx_cb (conn=0x5f957ddba4a0, res=49, msg=0x5f957de3e750) at ../../src_copy/libosmo-sigtran/src/ss7_asp.c:895
 #8  0x000076bb988efcb1 in stream_srv_iofd_read_cb (iofd=0x5f957ddd8e40, res=49, msg=0x5f957de3e750) at ../../src_copy/libosmo-netif/src/stream_srv.c:732
 #9  0x000076bb98b23c3c in iofd_handle_segmented_read (iofd=0x5f957ddd8e40, msg=0x5f957de3e750, rc=49) at ../../../src_copy/libosmocore/src/core/osmo_io.c:357
 #10 0x000076bb98b23d2b in iofd_handle_recv (iofd=0x5f957ddd8e40, msg=0x5f957de3e750, rc=49, hdr=0x0) at ../../../src_copy/libosmocore/src/core/osmo_io.c:384
 #11 0x000076bb98b257b7 in iofd_poll_ofd_cb_recvmsg_sendmsg (ofd=0x5f957ddd8ef0, what=1) at ../../../src_copy/libosmocore/src/core/osmo_io_poll.c:64
 #12 0x000076bb98b25b32 in iofd_poll_ofd_cb_dispatch (ofd=0x5f957ddd8ef0, what=1) at ../../../src_copy/libosmocore/src/core/osmo_io_poll.c:136
 #13 0x000076bb98b2907b in poll_disp_fds (n_fd=6) at ../../../src_copy/libosmocore/src/core/select.c:419
 #14 0x000076bb98b29191 in _osmo_select_main (polling=0) at ../../../src_copy/libosmocore/src/core/select.c:457
 #15 0x000076bb98b291ac in osmo_select_main (polling=0) at ../../../src_copy/libosmocore/src/core/select.c:496
 #16 0x00005f9553dd9a21 in main (argc=3, argv=0x7ffe754fac38) at ../../src_copy/libosmo-sigtran/stp/stp_main.c:270
"""

Related: OS#6728
Change-Id: I69f80f611c14db2b328dafd4a90247c6f2dac6fd
---
M src/ss7_asp.c
1 file changed, 24 insertions(+), 0 deletions(-)